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Effects of microclimate during transport on physiological indicators of market pig welfare: a systematic review with meta-analysis

Rick O. Hernandez, A. Rocha, Chao Cai, Marisa A. Erasmus, Jay S. Johnson, Luiz F. Brito

Frontiers in Veterinary Science, 2025

4 citations

Abstract

During transportation, microclimatic conditions can fluctuate significantly, affecting pigs’ thermal comfort and leading to compromised welfare and production losses. Although numerous studies have examined the effects of heat stress during transport on pig welfare and meat quality, it remains unclear whether these effects persist across varying transport scenarios and environmental conditions. Therefore, this systematic review and meta-analysis evaluated the effects of microclimate during transport on physiological welfare indicators in market pigs and summarized methodologies for assessing microclimate in commercial settings. Following PRISMA guidelines, 21 studies from three databases were used. Meta-regression analyses assessed microclimatic effects and trip duration on physiological indicators, including ultimate pH (pHu), creatine kinase (U/L), lactate (mmol/L), skin lesion score (0–5), skin temperature (°C), and blood cortisol (ng/mL). The studies retrieved used different equations to determine temperature-humidity index and enthalpy to describe microclimate dynamics. Ambient temperature was significantly associated with trailer temperature (β = 0.93 ± 0.12; p < 0.01). However, ambient relative humidity showed a lower magnitude association with trailer relative humidity (β = 0.51 ± 0.00; p < 0.001). Adverse microclimate conditions represented by high enthalpy (H) were associated with increases in creatine kinase (β = 3,715 ± 94.11; p < 0.001), lactate (β = 0.45 ±…

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